He made his a appeal at a solemn mass in St Peter's Basilica ending a two week Vatican summit of bishops from the Middle East, whose final document criticized Israel and urged the Jewish state to end its occupation of Palestinian territories.
In his sermon at the gathering's ceremonial end, the pope said freedom of religion was "one of the fundamental human rights that each state should always respect."
He said that while some states in the Middle East allowed freedom of belief, "the space given to the freedom to practice religion is often quite limited."
At least 3.5 million Christians of all denominations live in the Gulf Arab region, the birthplace of Islam and home to some of the most conservative Arab Muslim societies in the world.
The freedom to practice Christianity -- or any religion other than Islam -- is not always a given in the Gulf and varies from country to country. Saudi Arabia, which applies an austere form of Sunni Islam, has by far the tightest restrictions.
The Pope said all citizens in Middle Eastern countries would benefit from greater freedom of religion and backed a call by the synod participants for Muslims and Christians to open an "urgent and useful" dialogue on the thorny issue.
In Saudi Arabia, home to Islam's holiest sites, any form of non-Muslim worship takes place in private.
Converting Muslims is punishable by death, although such sentences are rare.
Services and prayer meetings often are held in diplomats' homes, but access to these is very limited, so Christians meet to worship in hotel conference rooms -- at great risk.
PEACE WILL STOP CHRISTIAN EXODUS
Trying to bring about a Middle East peace with a two-state solution was a main theme of the synod participants and the pope took up their plea in his homily.
"Peace is possible. Peace is urgent. Peace is an indispensable condition for a life worthy of the human person and of society. Peace is also the best remedy to avoid immigration from the Middle East," he said.
In its concluding message, issued on Saturday after two weeks of meetings, the synod said Israel cannot use the biblical concept of a promised land or a chosen people to justify new settlements in Jerusalem or territorial claims.
Many Jewish settlers and right-wing Israelis claim a biblical birthright to the occupied West Bank, which they call Judea and Samaria and regard as a part of historical, ancient Israel given to the Jews by God.
In a response, Israeli Foreign Ministry spokesman Yigal Palmor said theological disputes over the interpretation of the holy scriptures disappeared with the Middle Ages, adding: "It doesn't seem like a wise move to revive them."